wilson_smyth

looking for a general commuter bike. Not going to be a master of anything but will hopefully be reasonable in a few areas.
Commuting, with weekend leisure cycles, some being on trails. This narrows choices down to gravel and cross bikes.

The gravel/cx bikes i have access to come with these choices:

Shimano 105: Front 50 x 34t, Rear 11 - 34 x 11 (22 gears)
Shimano GRX: Front 40t, Rear 11 - 42t (11 gears)
Shimano GRX: Front 46-30t, Rear 11-34t (22 gears)

Im familiar with the gearing on the 22 gear 105, and spend most of my time on the big front cog and in the smallest 5 rear cogs.

For a reasonable spin (3-4 hours) how do the GRX compare to the 105, which is pretty good as a commuter as it has( in my opinion) a good range.

Kapusta

Compared the 105 50/34:

The GRX has a hair lower low gear... but so close it is not much different. Significantly lower high gear. Also bigger gaps between gear ratios.

Shimano 46/30 setup: lower high, lower low, similar gear ratio spacing.

As far as what will work best for you, you may as well be asking what shoe size to wear.

If you spend all your time in your 5 highest gears on a 50/34 x 11-34 setup, I can’t see why you would switch to a setup with lower range. Unless you plan to be riding different terrain. In which case you are going to need to look at the above comparisons and decide for yourself.

Maelochs

People will no doubt post gear-inch calculators .... or you could google them.

We have no idea what cassette you have, but you can find out, and figure out what the gear rations (or gear inches, whichever) are for the combos you most use, and then see what the 46-30 offers with the 11-34 cassette.

I'd imagine,. but it would be a completely wild guess, that you would be riding the top half of the cassette with the 46 ring. I have a 48-38-28 triple with a 14-34 on my old Cannondale, and spend almost all my time in the top couple cogs on the big ring on the flats ... it is just slightly undergeared for my preferences (unloaded. Loaded, it is great.) The 46-30 rings might be a bit too small for you ... but run them through a calculator and see.

TeakAsh

If you are unfamiliar with what works well for you, I would suggest going with the 46-30 GRX. In my opinion its better to have a bike that's under-geared, but you can climb almost anything, to a bike that's over-geared that forces you to walk.

subgrade

I've found that a comfortable cruising gear matters more than the high and low gears, at least on flat terrain. It may change with your fitness though. Of course, it's les of a problem on a a closely spaced 'corncob' casette.

Cyclist0108

Bicycle Gear Calculator